Re: [RFC][PATCH 2/7] writeback: fix queue_io() ordering
From: Jan Kara
Date: Wed Sep 09 2009 - 11:53:37 EST
On Wed 09-09-09 22:51:43, Wu Fengguang wrote:
>
This was not a bug, since b_io is empty for kupdate writeback.
>
The next patch will do requeue_io() for non-kupdate writeback,
>
so let's fix it.
But doesn't this patch also need your "anti-starvation" patch?
Looking into the code, we put inode to b_more_io when nr_to_write
drops to zero and this way we'd just start writing it again
in the next round...
Honza
>
>
CC: Dave Chinner <david@xxxxxxxxxxxxx>
>
Cc: Martin Bligh <mbligh@xxxxxxxxxx>
>
Cc: Michael Rubin <mrubin@xxxxxxxxxx>
>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
>
Signed-off-by: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
>
---
>
fs/fs-writeback.c | 7 +++++--
>
1 file changed, 5 insertions(+), 2 deletions(-)
>
>
--- linux.orig/fs/fs-writeback.c 2009年09月09日 21:41:14.000000000 +0800
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+++ linux/fs/fs-writeback.c 2009年09月09日 21:45:15.000000000 +0800
>
@@ -313,11 +313,14 @@ static void move_expired_inodes(struct l
>
}
>
>
/*
>
- * Queue all expired dirty inodes for io, eldest first.
>
+ * Queue all expired dirty inodes for io, eldest first:
>
+ * (newly dirtied) => b_dirty inodes
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+ * => b_more_io inodes
>
+ * => remaining inodes in b_io => (dequeue for sync)
>
*/
>
static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this)
>
{
>
- list_splice_init(&wb->b_more_io, wb->b_io.prev);
>
+ list_splice_init(&wb->b_more_io, &wb->b_io);
>
move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this);
>
}
>
>
>
--
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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